Synergistic Zn/Al Co-Doping and Sodium Enrichment Enable Reversible Phase Transitions in High-Performance Layered...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Layered transition-metal oxides are promising sodium-ion battery cathodes.
• Prototypical P2-Na0.67Ni0.33Mn0.67O2 (NM) suffers from irreversible phase transitions and capacity fade at high voltages.

Purpose of the Study:

• To develop a cooperative regulation strategy for enhancing the stability and performance of sodium-ion battery cathodes.
• To synthesize and characterize a novel P2-Na0.80Ni0.14Zn0.14Mn0.58Al0.14O2 (NMZA-N14) material.

Main Methods:

• Cooperative regulation strategy involving Zn/Al co-doping and Na enrichment.
• Synthesis of P2-Na0.80Ni0.14Zn0.14Mn0.58Al0.14O2 (NMZA-N14).
• Electrochemical performance testing (cycling, rate capability), kinetic analysis, and in situ X-ray diffraction.

Main Results:

• NMZA-N14 exhibits high initial discharge capacity (125 mAh g-1 at 0.1C) and excellent cycling stability (98.6% capacity retention after 100 cycles at 0.2C).
• Improved Na+ diffusion coefficient and lower charge-transfer resistance indicate accelerated ion transport.
• In situ XRD confirms a reversible P2 → OP4 phase transition with minimal volume change (~2.27%), preventing structural degradation.

Conclusions:

• Synergistic modulation via Zn/Al co-doping and Na enrichment significantly enhances structural stability and electrochemical kinetics.
• The developed NMZA-N14 material offers a viable pathway for designing high-performance sodium-ion battery cathodes.
• This strategy effectively suppresses irreversible phase transitions and capacity fade in layered transition-metal oxides.